Why don`t you listen to RAY??

Maybe, but it really doesn't sound like you're having cooling systems problems. Or are you?

Sounds like moisture and crud buildup has damaged the fuel delivery system.
Just a few things to check and do, recheck the inlet screen on the low pressure pump inlet for more debris or clogging.
If the fuel rail is rusted inside, replace it, the ehtanol fuel and moisture will keep it rusting and it will damage the injectors again.
Your fuel pressure is dropping when the motor starts to pull back so that means something in the fuel delivery is doing one of two things, one flowing lower volume whcih can drop pressure or something is dropping pressure which delivers less volume.
Either one will do what you are seeing with the engine.

You can also check that crankshaft sensor as I mentioned , but be careful when turning and removing it if it rusted in place as you can snap it off and thats a big problem.

Best Regards,
Ray @ Raylar

I am and have been....what makes you think I'm not?

I've contacted AIS Accurate in Az and will be sending the injectors to be flow tested, cleaned and rebuilt. However, my concern is not the injectors at this point. I'm thinking that if they were restricted enough to cause an issue then the boat would not run at all at higher rpms where more flow is needed. Yes it's obvious that the filters inside the injectors will have debris in them, no doubt about it... but I would be hard pressed to think that the injectors alone are the culprit due to the performance I'm experiencing.

I've also called into a few places to get pricing on a new/upgraded fuel rail.

Thanks

Well...I'm not dead set against having some sort of cooling/temp issue. After all, once I run for a while the motor and everything attached to it does "warm up" to some degree and that's when the backfiring/ shutdown occurs. But the temp gauge never goes above 163 deg.

I did read where someone had a t stat replaced and the carrier was left out which allowed water to flow past it to the sending unit for the gauge, but never opened up to allow water to flow thru the block, causing the issue... I haven't pulled the t stat yet.

My question is still, what all is involved with the heat exchanger? If there is something internal that acts like a t stat... opening and closing based on temp, then maybe that component is failing which is causing the one side of the exchanger to be much hotter than the other.

I believe you're reaching here. 163 is a good number and one side of the exchanger is naturally warmer duriing normal operation. There's nothing in the exchanger itself but two sets of isolated tubes. The T-stat is located at the coolent inlet port of the exchanger on the underside. If the engine warms up from cold to 163 then stabilizes the T-stat is working as it should.

Check that crankshaft sensor issue also.

Best Regards,
Ray @ Raylar

My issue with the crank sensor was not the same as yours, but I would also suggest looking into that. Here was my experience.

http://www.offshoreonly.com/forums/g...t-no-code.html

The local shop has a crank sensor in stock so i'll try that. I'm just gun shy to throw a hp fuel kit on it right away... Afterall I'm being quoted $420, and i dont know that is for sure my issue. But... B.O.A.T... Is was it's turning out to be.

Also called Formula today and they are researching any issues/warranty info I may have based on the HID and serial number of the engine.